In general, the ear microphone is used to be worn on ears of a user while the ear microphone is coupled with an external apparatus such as sound equipment or a mobile phone as is done in a general earphone.
FIG. 1 illustrates a schematic configuration of a conventional ear microphone.
Referring to FIG. 1, the ear microphone consists of a connector 10 to be coupled with an external apparatus 1, and a main body 20 to be worn on ears of the user. The main body 20 is shaped to be inserted into the ear of the user and includes a speaker 22 outputting a voice signal and a microphone 23 converting the voice signal delivered through the external auditory meatus of the user into an electric signal and outputting the electric signal to the connector 10 in a surface facing the ear of the user.
In the case of the ear microphone, an external noise is introduced into the ear microphone to cause the echo or howling phenomenon to occur.
The levels of the output voltage output from the output port of the mobile communication device such as a mobile phone or a smartphone to the ear microphone jack are different depending on the kind of the mobile phone or the smartphone.
In addition, the levels of the output voltage output from the output port of the mobile communication device to the ear microphone jack are different even when the kinds of the mobile phone or the smartphone are identical to one another. Accordingly, the echo and howling phenomena may occur due to the difference in output voltage level when the user has a conversation with his/her counterpart using the microphone implemented in the ear microphone. In particular, the phenomena become worse in the ear microphone in which the speaker and the microphone are integrally formed.